1. Field of the Invention
The invention pertains to a microscope objective with at least one correcting mount adjustable for different cover slip thickness.
2. Description of the Prior Art
A microscope objective for the compensation of different cover slip thicknesses is known from DE 38 12 745 AL, which has four lens groups, of which the second and the fourth lens group are movable, whereby both are counter-rotated towards each other. The mount of this objective contains an outer ring, which is attached to the case, into which an additional fixed ring is screwed, which has an inner thread for a there rotatably mounted intermediate ring. This intermediate ring has a cam, which engages into the notch of an operating ring, which can be rotated around the fixed ring. The rotatable intermediate ring has two spiral grooves with opposite-running and differently steep pitches. Into these grooves engages a cam, which is attached to the mount of the fourth lens element as well as a cam, which is screwed into the mount ring of the second lens group. These cams engage furthermore through axial slits into a mount ring, as well as its surrounding carrier hull, which contains the mount ring of the front lens group as well as all other lens mounts. A cam protects the carrier hull against distortion, so that the lens elements move axially when the operating ring is rotated without rotating themselves.
Furthermore a microscope objective with a correcting mount especially for different plane-parallel plate thicknesses in the object space is known from DE 37 35 324 AL, which has only one movable front lens group for image distortion correction, whereby a focal-plane correction occurs at the same time, through axial movement of the entire optical system. For this purpose it consists of two movable lens groups, of which the front lens group is moved with an operating ring through a motion-thread axially relative to the second lens group, while both lens groups are moved in a gliding tube relative to a fixed tube with that same operating ring.
These known microscope objectives with correcting mounts share the axial movement of one or several lens groups in order to compensate different cover slip thicknesses. The moving of a correcting mount within a cylindrical mount ring in exclusively axial direction however leads to tilting of the correcting mount around the optical axis, if its height in relation to the inner diameter of the mount ring is small, i.e. smaller than 0.6 times of this diameter. In the extreme case, i.e. with large diameter mount rings and correction rings of small height jamming of the mounts may occur.